1. Field of the Invention
The present invention relates to a method for building a road bed.
2. Description of the Related Art
Our earlier Patent application FI 894535 discloses a method for producing a joint structure formed of a combination of a shaped plate, generally a profiled steel plate, and concrete shotcreted on the shaped plate. An expanded sheet metal mesh manufactured thin steel sheet by elongation, is known from U.S. Pat. No. 1,864,598 and 3,034,197. A widermeshed diagonal screen grid manufactured from thicker sheet metal by cutting and elongation is known from U.S. Pat. No. 3,570,086.
A drawback in the current road-building methods is that a road bed requires the soil masses, which often leads to undesired the depressions in the soft ground underneath. The elimination of the depressions requires expensive ground reinforcements. Indeed, the construction of road beds on soft basic ground generally incurs major expense and extra costs.
Building passages in road-bed structures by the application of the prior known methods is expensive and inconvenient. Particularly, the casting of concrete into an arched vaulted shape is difficult and tedious. Carrying great masses of soil to a road-construction site requires a lot of time and causes environmental problems. The soil materials suitable for road-building are nearly exhausted in many places and must often be excavated in areas valuable in terms of environmental protection. Construction on soft grounds may take several years, as the reinforcement of subsoil is a tedious procedure. The road surfaces do not often remain flat, but develop traffic-disturbing depressions.
At present, road beds used as soil storages are useless especially in urban areas, for example where, the street sections are highly valuable areas. These road beds should be in service for more useful priorities other than the storage of sand.